IPO does not set that up - IPO is for making dining and recreation reservations, golf reservations, etc. You need to coordinate flowers/balloons/wine/gifts with the Disney Florist. The people there are called Dream Makers. You can call a Dream Maker at 407-WDW-GIFT. You can also email them at
DisneyDreamMaker@disney.com. They do in-room stuff at designated times (while you are out to dinner, etc) or will deliver stuff to the front desk for you to pick up later or for the front desk to deliver to the room. The Dream Makers will go as crazy or elaborate as you want. Some of the stuff they do is absolutely amazing!!!
If you want to send it by USPS overnight mail to the front desk to hold for you upon check-in, that's your choice but no way would I do that. Any CM could sign for it at the front desk, then it will lay around in the runner's cage or on the front desk just waiting for you to get there to pick it up. That would be very very very unsafe in my opinion. It could easily get misplaced or lost.
Personally I would never mail anything of that value but if I absolutely had to I would probably go with fed ex, insured, signature required.
Normal hours of business center/shipping department is 7AM to 7PM. I do not know if the hours will be different on Columbus Day.